Like a bit of froth on the crest of an ocean wave, our observable universe may be nothing more than a sliver sitting within the edge of a bubble that’s constantly expanding into a higher dimension.
While this mind-boggling idea might sound like something out of a physicist’s fever dream, it is in fact a new endeavor to reconcile the mathematics of string theory with the reality of dark energy, a mysterious, all-pervading cosmic force that acts in opposition to gravity.
String theory is an attempt to unite the two pillars of 20th century physics — quantum mechanics and gravity — by positing that all particles are one-dimensional strings whose vibrations determine properties such as mass and charge. The theory has been described as mathematically beautiful, and for a long time has been one of the leading contenders for what scientists call a Theory of Everything, meaning a framework to explain all physics, popularized in books like Brian Greene’s The Elegant Universe (Norton, 1999). [Big Bang to Civilization: 10 Amazing Origin Events]
But string theorists have lately been lost in a warren of their own speculations. Many versions of string theory require that reality consist of 10 or more dimensions — the three of space and one of time we normally experience, plus many others that are rolled up into an extremely tight point. Exactly how those extra dimensions are configured determines the characteristics of the universe we perceive.